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<head>
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    <!-- 一定不要忘记引入bootstrap 的样式文件 -->
    <link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">
    <title>Document</title>
    <style>
        [class^="col"] {
            border: 1px solid #ccc;
        }
        
        .row:nth-child(1) {
            background-color: pink;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="row">
            <div class="col-lg-3 col-md-4 col-sm-6 col-xs-12">1</div>
            <div class="col-lg-3 col-md-4 col-sm-6 col-xs-12">2</div>
            <div class="col-lg-3 col-md-4 col-sm-6 col-xs-12">3</div>
            <div class="col-lg-3 col-md-4 col-sm-6 col-xs-12">4</div>
        </div>
        <!-- 如果孩子的份数相加等于12 则孩子能占满整个 的container 的宽度 -->
        <div class="row">
            <div class="col-lg-6">1</div>
            <div class="col-lg-2">2</div>
            <div class="col-lg-2">3</div>
            <div class="col-lg-2">4</div>
        </div>
        <!-- 如果孩子的份数相加 小于 12 则会？ 则占不满整个container 的宽度 会有空白 -->
        <div class="row">
            <div class="col-lg-6">1</div>
            <div class="col-lg-2">2</div>
            <div class="col-lg-2">3</div>
            <div class="col-lg-1">4</div>
        </div>
        <!-- 如果孩子的份数相加 大于 12 则会？多于的那一列会 另起一行显示  -->

        <div class="row">
            <div class="col-lg-6">1</div>
            <div class="col-lg-2">2</div>
            <div class="col-lg-2">3</div>
            <div class="col-lg-3">4</div>
        </div>


    </div>
</body>

</html>